A copy of the Magna Carta sold for the princely sum of $21.3 million yesterday.

The 13th century document, which curbed the power of the British monarchy and inspired the framers of the US Constitution, was bought by billionaire Carlyle Group co-founder David Rubenstein at Sotheby’s New York.

“I’ve always believed it was an important document in our country, therefore I’m privileged to be the owner,” he said. The copy, one of only 17 in existence, was put up for auction by former independent presidential candidate Ross Perot, who will give the money to his charitable foundation.

It is the only copy of the Magna Carta in the United States, and the new owner plans to keep it here, displaying it at the National Archives. “I thought it was very important that the Magna Carta stay in the US,” Rubenstein said. “I feared it would escape and go to another country.”

Britain’s King John was forced to sign the Magna Carta in 1215. The copy sold yesterday, which Sotheby’s had valued between $20 million and $30 million was from 1297, the year it was enacted as law.